title: New insights into the sorption mechanism of cadmium on red mud.
abstract: Effectiveness and mechanism of cadmium (Cd) sorption on original, acidified and ball milling nano-particle red muds were investigated using batch sorption experiments, sequential extraction analysis and X-ray absorption near edge structure (XANES) spectroscopy. The maximum sorption capacity of Cd was 0.16, 0.19, and 0.21 mol/kg for the original, acidified, and nano-particle red muds at pH 6.5, respectively. Both acidification and ball-milling treatments significantly enhanced Cd sorption and facilitated transformation of Cd into less extractable fractions. The Cd LIII-edge XANES analysis indicated the formation of inner-sphere complexes of Cd similar to XCdOH (X represents surface groups on red mud) on the red mud surfaces although outer-sphere complexes of Cd were the primary species. This work shed light on the potential application of red mud to remediate Cd-contaminated soils and illustrated the promising tool of XANES spectroscopy for speciation of multicomponent systems of environmental relevance.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Luo
authors.forename: Chenyan
authors.initials: C
authors.lastname: Ma
authors.forename: Yibing
authors.initials: Y
authors.lastname: Ma
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Zhang
authors.forename: Jitao
authors.initials: J
authors.lastname: Lv
authors.forename: Mingqi
authors.initials: M
authors.lastname: Cui
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D008669:Metallurgy; D053758:Nanoparticles / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D007220:Industrial Waste; D002104:Cadmium